Compare gypsum and cement plaster

We decid­ed to ask the experts if there is a fun­da­men­tal dif­fer­ence between gyp­sum and cement plas­ter, and whether they can be com­bined. The opin­ions of the builders turned out to be con­tra­dic­to­ry, but we were able to draw some con­clu­sions for our­selves. In both cas­es, we are talk­ing about solu­tions used to lev­el walls and ceil­ings, giv­ing them a flat sur­face. Both gyp­sum-based com­po­si­tions and cement-sand mix­tures are very pop­u­lar, being ahead of com­peti­tors in many respects, and the choice depends on the char­ac­ter­is­tics of the premis­es and oth­er con­di­tions. More about this, but we will start with an analy­sis of the com­po­si­tion of mate­ri­als.

Composition of cement plaster

It is pos­si­ble to talk about the advan­tages of a par­tic­u­lar build­ing mate­r­i­al only by study­ing the com­po­si­tion. The pop­u­lar­i­ty of the cement-sand mix­ture is explained by many by the fact that it con­tains avail­able com­po­nents.

1. 1. Cement. The main binder is cement, the brand of which deter­mines the strength of the solu­tion and the dura­bil­i­ty of the coat­ing. If M400 cement is used for exte­ri­or work and lev­el­ing walls in rooms exposed to aggres­sive envi­ron­ments, then cheap­er M150 cement can be used for inte­ri­or work.

       

 

1. 1. Sand. To give strength and plas­tic­i­ty, dif­fer­ent fillers are used, but most often sand is used for these pur­pos­es, which dif­fers in ori­gin (riv­er, quar­ry, allu­vial) and frac­tion. Coarse-grained sand is ide­al for road con­struc­tion and foun­da­tion pour­ing, while fine-grained sand is most often the basis for plas­ter cement-sand mix­tures. Impor­tant! Experts do not rec­om­mend chas­ing sand of too fine a frac­tion, since the plas­ter mix­ture pre­pared on its basis can quick­ly crack. On the oth­er hand, when using coarse sand, be pre­pared for the fact that it will take a lot of time to grind the sur­face, so you need to find your “gold­en mean”.

       

 

1. 1. Water, the amount of which must also be select­ed in each indi­vid­ual case.

       

 

1. 1. Addi­tives improv­ing plas­tic­i­ty, vapor per­me­abil­i­ty and oth­er char­ac­ter­is­tics of the mate­r­i­al, and the most acces­si­ble of them is lime, but it must be slaked and aged for at least two weeks. If the lime is not cured, unde­sir­able bulges may appear on the sur­face.

       

 

1. 1. Poly­mer Addi­tivesimprov­ing the strength of the mate­r­i­al and its resis­tance to aggres­sive influ­ences, and many builders pre­fer PVA glue in this mat­ter, and again because of its avail­abil­i­ty.

       

 

Depend­ing on the fea­tures of use and the prop­er­ties that the plas­ter mix­ture should be endowed with, cement and sand are mixed in dif­fer­ent pro­por­tions, but as a stan­dard, three or four vol­umes of sand are used for one vol­ume of cement. Look­ing ahead, we want to say that it is the pos­si­bil­i­ty of exper­i­ment­ing with the quan­ti­ty and qual­i­ty of the com­po­nents used to pre­pare the mix­ture that experts con­sid­er the main advan­tage of the cement-sand mor­tar.

After lis­ten­ing to an alter­na­tive opin­ion, we came to the con­clu­sion that it is not nec­es­sary to pre­pare the cement mix­ture our­selves, and the qual­i­ty of mod­ern ready-made mix­tures based on already famil­iar com­po­nents is a vivid con­fir­ma­tion of this. As an argu­ment for con­nois­seurs of the “clas­sics”, one can cite espe­cial­ly durable poly­mer-cement mix­tures, which are dis­tin­guished by resis­tance to pre­ma­ture abra­sion, high resis­tance to impact and tem­per­a­ture extremes. Among the com­pa­nies involved in their pro­duc­tion, Knauf prod­ucts are on a spe­cial account. These are ready-to-use mix­tures used for rough and fin­ish fin­ish­ing.

The composition and features of gypsum plaster

Gyp­sum plas­ter - this is a whole group of ready-made mix­tures used main­ly for inte­ri­or dec­o­ra­tion of premis­es with a nor­mal humid­i­ty regime. It is easy to guess that the main binder here is gyp­sum pow­der. It is obtained from a nat­ur­al min­er­al, sub­ject­ed to pre-heat treat­ment and crush­ing. To reduce con­sump­tion, give the mix­ture strength and improve adhe­sion, nat­ur­al or syn­thet­ic fillers and poly­mer addi­tives are used.

Gyp­sum mix­tures are sup­plied in dif­fer­ent pack­ag­ing, they are com­plete­ly ready for use, for which it is enough to add the right amount of water. The “fat con­tent” of the solu­tion and the scope of its appli­ca­tion depend on the amount of liq­uid. If it is nec­es­sary to close a crack in the wall, the amount of water added should be min­i­mal. For fin­ish­ing (dec­o­ra­tive plas­ter), the solu­tion must be suf­fi­cient­ly liq­uid and spread well on the wall.

Advantages and disadvantages of cement plaster

A sim­ple analy­sis of the com­po­si­tion does not give a com­plete pic­ture and an answer to the ques­tion of which plas­ter mix­ture is prefer­able. Prac­ti­tion­ers can best tell about it. The advan­tages of cement-sand mor­tar, they include:

1. 1. high resis­tance to high humid­i­ty, which under­lies the use for out­door dec­o­ra­tion;

       

 

1. 1. high strength of plas­ter, which, with the cor­rect dosage of com­po­nents, can serve for a long time, resist­ing atmos­pher­ic and mechan­i­cal influ­ences;

       

 

1. 1. the plas­tic­i­ty of the mate­r­i­al, and the mix­ture pre­pared in advance can be used for sev­er­al hours;

       

 

1. 1. low cost and avail­abil­i­ty.

       

 

At the same time, builders talk about the short­com­ings of cement plas­ter, and it does not fit well on con­crete, which requires addi­tion­al sur­face treat­ment (etch­ing). Experts also note a long dry­ing time, and the cement mix­ture must with­stand at least two weeks, while for cement to crys­tal­lize, the fin­ished mix­ture must be sprin­kled with water for some time. After shrink­age, irreg­u­lar­i­ties may appear, and in order to avoid crack­ing, heat­ing devices should not be used to dry the premis­es. The cement mix­ture is heavy, so it is not suit­able for lev­el­ing ceil­ings. The cement has an unsight­ly gray col­or, so the facade of the build­ing requires fin­ish­ing cladding, which takes a lot of time and mon­ey.

Advantages and disadvantages of gypsum mixtures

Hav­ing assessed the advan­tages and dis­ad­van­tages of cement plas­ter, you can pro­ceed to the study of the prop­er­ties of gyp­sum mix­tures. Unlike a com­peti­tor, they have high adhe­sion, so they fit per­fect­ly on any sur­face and do not require addi­tion­al sur­face treat­ment. Gyp­sum coat­ing does not require addi­tion­al cladding, as the sur­face looks per­fect.

The con­sump­tion of gyp­sum plas­ter per square meter of sur­face is 1.5–2 times low­er than in the case of cement coat­ing, and this is a ques­tion of the cost of the mate­r­i­al. Among the advan­tages of the cement-sand mix­ture, many note the low cost com­pared to the gyp­sum coun­ter­part, but this issue is debat­able, since the price also dif­fers by one and a half to two times, so there is no need to talk about sav­ings. Do not for­get that the gyp­sum coat­ing has good sound and heat insu­la­tion prop­er­ties, unlike a mix­ture based on cement and sand. But not every­thing is as good as it turned out with gyp­sum, so I would like to talk sep­a­rate­ly about the short­com­ings of gyp­sum coat­ings:

1. 1. the sur­face plas­tered with a gyp­sum pow­der mor­tar is not resis­tant to mechan­i­cal dam­age, there­fore it is absolute­ly not suit­able for fin­ish­ing facades;

       

 

1. 1. gyp­sum is afraid of high humid­i­ty, and this also under­lies the use of the mate­r­i­al, and it is rec­om­mend­ed exclu­sive­ly for fin­ish­ing inte­ri­or sur­faces;

       

 

1. 1. it is nec­es­sary to work with gyp­sum mor­tar quick­ly, as it sets quick­ly, and there­fore the mix­ture is pre­pared in small quan­ti­ties, which increas­es the time for com­ple­tion of work;

       

 

1. 1. despite high adhe­sion, addi­tion­al fin­ish­ing of con­crete sur­faces and appli­ca­tion of a primer are required if it is nec­es­sary to plas­ter met­al sur­faces with­out water­proof­ing.

       

 

At the con­struc­tion site, three types of gyp­sum plas­ter are used: fine, medi­um and coarse-grained frac­tions. The fine-grained mix­ture is applied in a lay­er up to 0.8 mm, requires an addi­tion­al lay­er, and is used main­ly for plas­ter­ing ceil­ings. Gyp­sum plas­ter of medi­um-grained frac­tion, applied with a lay­er of up to 5 cm, is the main com­peti­tor to cement-sand coat­ings. A large frac­tion is used to hide sig­nif­i­cant sur­face defects, and often for facade cladding, but in the case of good water­proof per­for­mance. Rot­band gyp­sum plas­ter mix­tures are very pop­u­lar.

Gypsum and cement plaster in comparison

A com­par­a­tive analy­sis of the char­ac­ter­is­tics of gyp­sum and cement-sand plas­ter sug­gests that each of them has its own advan­tages, not with­out cov­er­age and dis­ad­van­tages. You can avoid pos­si­ble trou­bles by choos­ing the right mate­r­i­al, depend­ing on the fea­tures of oper­a­tion. Out­side the build­ing and in rooms with high humid­i­ty (bath­room, kitchen), it is def­i­nite­ly bet­ter to use cement mix­tures, and gyp­sum is bet­ter for fin­ish­ing inside build­ings, which does not require addi­tion­al cladding.

Use­ful advice: it is believed that gyp­sum is afraid of mois­ture, there­fore it is not used for plas­ter­ing bath­rooms, pools, kitchens and oth­er rooms with high lev­els of humid­i­ty. Experts rec­om­mend using var­nish for this pur­pose, which is applied on top of the plas­ter. Such a sur­face is not afraid of water, more­over, it looks per­fect.

Gyp­sum coat­ing looks more attrac­tive, it is plas­tic and easy to work with, and it’s hard to argue with that, but if you don’t have plas­ter­ing skills, then it’s bet­ter to learn on cement mor­tar. Gyp­sum dries up lit­er­al­ly before our eyes (10–15 min­utes), while reusing such a mix­ture is impos­si­ble, but this is an indis­pens­able prop­er­ty when lev­el­ing the ceil­ing and hard-to-reach places. For its part, the cement-sand coat­ing dries out only after a few hours, and dur­ing this time even a novice spe­cial­ist can plas­ter a large area.

Even an expe­ri­enced builder, hav­ing weighed all the pros and cons, can­not unequiv­o­cal­ly say whether it is bet­ter to use gyp­sum or cement plas­ter. With a large num­ber of obvi­ous advan­tages of gyp­sum, it should be under­stood that it is prac­ti­cal­ly not suit­able for fin­ish­ing facades, so there is no alter­na­tive to the cement-sand mix­ture. Mean­while, work­ing with cement plas­ter is more dif­fi­cult, so you can only do the work if you have the appro­pri­ate expe­ri­ence. Gyp­sum mix­es are more expen­sive, but their con­sump­tion is less, which also caus­es cer­tain dif­fi­cul­ties in choos­ing. It is nec­es­sary to take into account mul­ti­ple fac­tors, and in order for under­stand­ing to come faster, we have col­lect­ed all the infor­ma­tion pre­sent­ed in a table.

 

Char­ac­ter­is­tic	Gyp­sum plas­ter	cement plas­ter
Com­pound	Gyp­sum pow­der of dif­fer­ent frac­tions, poly­mer mod­i­fiers	Cement, sand, water, lime and some oth­er addi­tives (as need­ed)
Dry­ing speed of the fin­ished plas­ter	2–3 days, and if we are talk­ing about a thick coat­ing — up to 7 days	Two to four weeks (depend­ing on lay­er thick­ness, humid­i­ty and tem­per­a­ture)
mois­ture resis­tance	Low, there­fore, when used in rooms with high humid­i­ty, the use of pro­tec­tive com­pounds is rec­om­mend­ed	High, so it can be used in the bath­room, swim­ming pool, kitchen and facade cladding
Shrink­age	Not affect­ed	With­in 2mm per 1 meter
Aver­age con­sump­tion of mate­r­i­al at a lay­er thick­ness of 10 mm	10 kg per 1 sq. m.	17 kg per 1 sq. m.

Life hacks: how best to plaster a brick wall

Assess­ing the advan­tages of gyp­sum and cement plas­ter, our spe­cial­ists gave some use­ful rec­om­men­da­tions in par­al­lel on how best to plas­ter a brick wall.

Tip 1

Con­trary to the opin­ion that it is nec­es­sary to plas­ter the walls in cloudy weath­er, they are sure that it is bet­ter for the sun to be, but the air tem­per­a­ture was with­in 5–30 degrees above zero. It is also a proven fact that plas­ter dries bet­ter in the heat, but this will not ben­e­fit the sur­face, which is guar­an­teed to crack in the near future.

Tip 2

To improve the strength of cement plas­ter applied man­u­al­ly or by machine, it is nec­es­sary to use a hard­en­er in an amount of 1–2% of the total vol­ume of the mix­ture. In order for the sur­face to look per­fect, it is nec­es­sary to apply a lay­er of the same thick­ness over the entire sur­face.

Tip 3

When asked about the pos­si­bil­i­ty of lay­ing bricks on gyp­sum plas­ter, the builders answered unam­bigu­ous­ly in the neg­a­tive. Gyp­sum has a dif­fer­ent com­po­si­tion than the cement mix­ture used in brick­lay­ing, and it can also be eas­i­ly removed from the wall sur­face. It is bet­ter to lay a brick on top of cement-sand plas­ter, while both gyp­sum and cement mix­tures are not suit­able for lay­ing ordi­nary bricks.